Lighting fixtures can be automatically switched on at dusk and off at dawn using twist-lock photoelectric controllers. The lighting fixtures may be used to light roads, parking lots and other areas outdoors. The photoelectric controller senses the intensity of the ambient light and switches the lighting fixtures on and off as appropriate. The photoelectric controllers are typically oriented so that the photocell faces North, away from direct sunlight in the Northern hemisphere (and in a southerly direction in the Southern hemisphere). It is also desired to be able to easily adjust the receptacle that receives the photoelectric controller to achieve the desired orientation.
Lighting fixtures for street lights typically include an electrical receptacle that receives the photoelectric controller that is mounted to a housing on the top of the lighting fixture. The electrical receptacle is wired to the power supply of the lighting fixture. The photoelectric controller has three main terminals that are inserted into the electrical receptacle and twisted to lock the photoelectric controller to the receptacle.
The orientation of the photoelectric controller in the Northern direction is accomplished by the use of a metal snap ring having fingers that engage the electrical receptacle and urge it toward the housing of the lighting fixture using a spring force. This is disclosed in U.S. Pat. No. 4,477,143. The electrical receptacle may be lifted up against the spring force and turned to orient the receptacle North. Circumferential holes located in an upper circular end plate of the electrical receptacle receive pins formed around an opening in the housing for securing the electrical receptacle to the housing. In another approach in which no snap ring is used, the electrical receptacle is oriented by loosening a screw in the top of the receptacle, rotating the receptacle until indicia on the receptacle points to the desired position and then re-tightening the screw.